1 files changed, 255 insertions, 0 deletions
diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
new file mode 100644
index 000000000000..8b8a5a45b621
--- /dev/null
+++ b/arch/ia64/kernel/time.c
@@ -0,0 +1,255 @@
+/*
+ * linux/arch/ia64/kernel/time.c
+ *
+ * Copyright (C) 1998-2003 Hewlett-Packard Co
+ *	Stephane Eranian <eranian@hpl.hp.com>
+ *	David Mosberger <davidm@hpl.hp.com>
+ * Copyright (C) 1999 Don Dugger <don.dugger@intel.com>
+ * Copyright (C) 1999-2000 VA Linux Systems
+ * Copyright (C) 1999-2000 Walt Drummond <drummond@valinux.com>
+ */
+#include <linux/config.h>
+
+#include <linux/cpu.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/profile.h>
+#include <linux/sched.h>
+#include <linux/time.h>
+#include <linux/interrupt.h>
+#include <linux/efi.h>
+#include <linux/profile.h>
+#include <linux/timex.h>
+
+#include <asm/machvec.h>
+#include <asm/delay.h>
+#include <asm/hw_irq.h>
+#include <asm/ptrace.h>
+#include <asm/sal.h>
+#include <asm/sections.h>
+#include <asm/system.h>
+
+extern unsigned long wall_jiffies;
+
+u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES;
+
+EXPORT_SYMBOL(jiffies_64);
+
+#define TIME_KEEPER_ID	0	/* smp_processor_id() of time-keeper */
+
+#ifdef CONFIG_IA64_DEBUG_IRQ
+
+unsigned long last_cli_ip;
+EXPORT_SYMBOL(last_cli_ip);
+
+#endif
+
+static struct time_interpolator itc_interpolator = {
+	.shift = 16,
+	.mask = 0xffffffffffffffffLL,
+	.source = TIME_SOURCE_CPU
+};
+
+static irqreturn_t
+timer_interrupt (int irq, void *dev_id, struct pt_regs *regs)
+{
+	unsigned long new_itm;
+
+	if (unlikely(cpu_is_offline(smp_processor_id()))) {
+		return IRQ_HANDLED;
+	}
+
+	platform_timer_interrupt(irq, dev_id, regs);
+
+	new_itm = local_cpu_data->itm_next;
+
+	if (!time_after(ia64_get_itc(), new_itm))
+		printk(KERN_ERR "Oops: timer tick before it's due (itc=%lx,itm=%lx)\n",
+		       ia64_get_itc(), new_itm);
+
+	profile_tick(CPU_PROFILING, regs);
+
+	while (1) {
+		update_process_times(user_mode(regs));
+
+		new_itm += local_cpu_data->itm_delta;
+
+		if (smp_processor_id() == TIME_KEEPER_ID) {
+			/*
+			 * Here we are in the timer irq handler. We have irqs locally
+			 * disabled, but we don't know if the timer_bh is running on
+			 * another CPU. We need to avoid to SMP race by acquiring the
+			 * xtime_lock.
+			 */
+			write_seqlock(&xtime_lock);
+			do_timer(regs);
+			local_cpu_data->itm_next = new_itm;
+			write_sequnlock(&xtime_lock);
+		} else
+			local_cpu_data->itm_next = new_itm;
+
+		if (time_after(new_itm, ia64_get_itc()))
+			break;
+	}
+
+	do {
+		/*
+		 * If we're too close to the next clock tick for
+		 * comfort, we increase the safety margin by
+		 * intentionally dropping the next tick(s).  We do NOT
+		 * update itm.next because that would force us to call
+		 * do_timer() which in turn would let our clock run
+		 * too fast (with the potentially devastating effect
+		 * of losing monotony of time).
+		 */
+		while (!time_after(new_itm, ia64_get_itc() + local_cpu_data->itm_delta/2))
+			new_itm += local_cpu_data->itm_delta;
+		ia64_set_itm(new_itm);
+		/* double check, in case we got hit by a (slow) PMI: */
+	} while (time_after_eq(ia64_get_itc(), new_itm));
+	return IRQ_HANDLED;
+}
+
+/*
+ * Encapsulate access to the itm structure for SMP.
+ */
+void
+ia64_cpu_local_tick (void)
+{
+	int cpu = smp_processor_id();
+	unsigned long shift = 0, delta;
+
+	/* arrange for the cycle counter to generate a timer interrupt: */
+	ia64_set_itv(IA64_TIMER_VECTOR);
+
+	delta = local_cpu_data->itm_delta;
+	/*
+	 * Stagger the timer tick for each CPU so they don't occur all at (almost) the
+	 * same time:
+	 */
+	if (cpu) {
+		unsigned long hi = 1UL << ia64_fls(cpu);
+		shift = (2*(cpu - hi) + 1) * delta/hi/2;
+	}
+	local_cpu_data->itm_next = ia64_get_itc() + delta + shift;
+	ia64_set_itm(local_cpu_data->itm_next);
+}
+
+static int nojitter;
+
+static int __init nojitter_setup(char *str)
+{
+	nojitter = 1;
+	printk("Jitter checking for ITC timers disabled\n");
+	return 1;
+}
+
+__setup("nojitter", nojitter_setup);
+
+
+void __devinit
+ia64_init_itm (void)
+{
+	unsigned long platform_base_freq, itc_freq;
+	struct pal_freq_ratio itc_ratio, proc_ratio;
+	long status, platform_base_drift, itc_drift;
+
+	/*
+	 * According to SAL v2.6, we need to use a SAL call to determine the platform base
+	 * frequency and then a PAL call to determine the frequency ratio between the ITC
+	 * and the base frequency.
+	 */
+	status = ia64_sal_freq_base(SAL_FREQ_BASE_PLATFORM,
+				    &platform_base_freq, &platform_base_drift);
+	if (status != 0) {
+		printk(KERN_ERR "SAL_FREQ_BASE_PLATFORM failed: %s\n", ia64_sal_strerror(status));
+	} else {
+		status = ia64_pal_freq_ratios(&proc_ratio, NULL, &itc_ratio);
+		if (status != 0)
+			printk(KERN_ERR "PAL_FREQ_RATIOS failed with status=%ld\n", status);
+	}
+	if (status != 0) {
+		/* invent "random" values */
+		printk(KERN_ERR
+		       "SAL/PAL failed to obtain frequency info---inventing reasonable values\n");
+		platform_base_freq = 100000000;
+		platform_base_drift = -1;	/* no drift info */
+		itc_ratio.num = 3;
+		itc_ratio.den = 1;
+	}
+	if (platform_base_freq < 40000000) {
+		printk(KERN_ERR "Platform base frequency %lu bogus---resetting to 75MHz!\n",
+		       platform_base_freq);
+		platform_base_freq = 75000000;
+		platform_base_drift = -1;
+	}
+	if (!proc_ratio.den)
+		proc_ratio.den = 1;	/* avoid division by zero */
+	if (!itc_ratio.den)
+		itc_ratio.den = 1;	/* avoid division by zero */
+
+	itc_freq = (platform_base_freq*itc_ratio.num)/itc_ratio.den;
+
+	local_cpu_data->itm_delta = (itc_freq + HZ/2) / HZ;
+	printk(KERN_DEBUG "CPU %d: base freq=%lu.%03luMHz, ITC ratio=%lu/%lu, "
+	       "ITC freq=%lu.%03luMHz", smp_processor_id(),
+	       platform_base_freq / 1000000, (platform_base_freq / 1000) % 1000,
+	       itc_ratio.num, itc_ratio.den, itc_freq / 1000000, (itc_freq / 1000) % 1000);
+
+	if (platform_base_drift != -1) {
+		itc_drift = platform_base_drift*itc_ratio.num/itc_ratio.den;
+		printk("+/-%ldppm\n", itc_drift);
+	} else {
+		itc_drift = -1;
+		printk("\n");
+	}
+
+	local_cpu_data->proc_freq = (platform_base_freq*proc_ratio.num)/proc_ratio.den;
+	local_cpu_data->itc_freq = itc_freq;
+	local_cpu_data->cyc_per_usec = (itc_freq + USEC_PER_SEC/2) / USEC_PER_SEC;
+	local_cpu_data->nsec_per_cyc = ((NSEC_PER_SEC<<IA64_NSEC_PER_CYC_SHIFT)
+					+ itc_freq/2)/itc_freq;
+
+	if (!(sal_platform_features & IA64_SAL_PLATFORM_FEATURE_ITC_DRIFT)) {
+		itc_interpolator.frequency = local_cpu_data->itc_freq;
+		itc_interpolator.drift = itc_drift;
+#ifdef CONFIG_SMP
+		/* On IA64 in an SMP configuration ITCs are never accurately synchronized.
+		 * Jitter compensation requires a cmpxchg which may limit
+		 * the scalability of the syscalls for retrieving time.
+		 * The ITC synchronization is usually successful to within a few
+		 * ITC ticks but this is not a sure thing. If you need to improve
+		 * timer performance in SMP situations then boot the kernel with the
+		 * "nojitter" option. However, doing so may result in time fluctuating (maybe
+		 * even going backward) if the ITC offsets between the individual CPUs
+		 * are too large.
+		 */
+		if (!nojitter) itc_interpolator.jitter = 1;
+#endif
+		register_time_interpolator(&itc_interpolator);
+	}
+
+	/* Setup the CPU local timer tick */
+	ia64_cpu_local_tick();
+}
+
+static struct irqaction timer_irqaction = {
+	.handler =	timer_interrupt,
+	.flags =	SA_INTERRUPT,
+	.name =		"timer"
+};
+
+void __init
+time_init (void)
+{
+	register_percpu_irq(IA64_TIMER_VECTOR, &timer_irqaction);
+	efi_gettimeofday(&xtime);
+	ia64_init_itm();
+
+	/*
+	 * Initialize wall_to_monotonic such that adding it to xtime will yield zero, the
+	 * tv_nsec field must be normalized (i.e., 0 <= nsec < NSEC_PER_SEC).
+	 */
+	set_normalized_timespec(&wall_to_monotonic, -xtime.tv_sec, -xtime.tv_nsec);
+}